Light-sensitive silver halide photographic emulsion for microfilm use

ABSTRACT

SILVER HALIDE PHOTOGRAPHIC EMULSIONS FOR MICROFILM USE ARE SENSITIZED BY INCORPORATING THEREINTO, TWO OR MORE DYES OF THE FORMULA (I) AND ONE COMPOUND OF THE FORMULA (II) IN COMBINATIN: (-N(-R1)-Z-)&gt;C=CH-C(-R2)=CH-C&lt;(-Z-N(+)(-R3)=) (X(-))(R-1)   2-((3-R4,5-Y1,6-Y2-2,3-DIHYDROBENZOXAZOL-2-YLIDENE=CH-CH= CH-),1-R5,3-R6,(CL)N-BENZOXAZOLIUM (X(-))(M-1) WHEREIN R1, R3, R4 AND R6 ARE INDEPENDENTLY SELECTED FROM THE GROUP CONSISTING OF LOWER ALKYL GROUP, A CARBOXYALKYL GROUP OR A SULFOALKYL GROUP, WITH THE PROVISO THAT AT LEAST ONE OF R1, R3, R4 AND R6 IS A CARBOXYALKYL, SULFOALKYL OR SULFALKOXYALKYL GROUP; R2 IS HYDROGEN ATOM OR A LOWER ALKYL GROUP; R5 IS A LOWER ALKYL GROUP; Y IS HYDROGEN ATOM, CHLORINE ATOM, A LOWER ALKYL GROUP OR A LOWER ALKOXY GROUP; Y2 IS HYDROGEN ATOM OR A LOWER ALKYL GROUP WITH THE PROVISO THAT WHEN Y1 IS CHLORINE, Y2 IS METHYL; Z IS A GROUP CAPABLE OF FORMING, TOGETHER WITH THE ADJACENT NITROGEN AND CARBON ATOMS, A HETEROCYCLIC RING; X IS AN ANION; AND 1, N AND M ARE EACH 1 OR 2.

Nov. 7, 1972 SHUI SATO ETAL 3,702,251

LIGHT-SENSITIVE SILVER HALIDE PHOTOGRAPHIC EMULSION FOR MICROFILM USE Filed Dec. 9, 1968 F/Gi F/GI2 l l l l l l l WAVEZE/VGT 4 00 5'00 650 7&0

11 41/[1 AWG/A/ 0 4 United States Patent 3,702,251 LIGHT-SENSITIVE SILVER HALIDE PHOTO- GRAPHIC EMULSION FOR MICROFILM USE Shui Sato, Kaiichiro Sakazume, and Tsuneo Suga, Tokyo,

Japan, assiguors to Konishiroku Photo Industry Co.,

Ltd., Tokyo, Japan Filed Dec. 9, 1968, Ser. No. 782,169 Int. Cl. G03c 1/14 US. Cl. 96-124 6 Claims ABSTRACT OF THE DISCLOSURE Silver halide photographic emulsions for microfilm use are sensitized by incorporating thereinto, two or more dyes of the Formula (I) and one compound of the Formula (II) in combination:

wherein R R R and R are independently selected from the group consisting of lower alkyl group, a carboxyalkyl group or a sulfoalkyl group, with the proviso that at least one of R R R and R is a carboxyalkyl, sulfoalkyl or sulfalkoxyalkyl group; R is hydrogen atom or a lower alkyl group; R is a lower alkyl group; Y is hydrogen atom, chlorine atom, a lower alkyl group or a lower alkoxy group; Y is hydrogen atom or a lower alkyl group with the proviso that when Y is chlorine, Y, is methyl; Z is a group capable of forming, together with the adjacent nitrogen and carbon atoms, a heterocyclic ring; X is an anion; and 1, n and m are each 1 or 2.

This invention relates to sensitized light-sensitive silver halide photographic emulsions for microfilm use. More particularly this invention relates to a light-sensitive silver halide photographic emulsion suited for microfilm, which comprises two or more sensitizing dyes of the general Formula (I) in combination with one sensitizing dye of the general Formula II:

wherein R R R and R are independently selected from the group consisting of a lower alkyl radical, a carboxy- 3,702,251 Patented Nov. 7, 1972 alkyl group, a sulfoalkyl group and a sulfoalkoxyalkyl group; R, is hydrogen atom or a lower alkyl group; R is an alkyl group, with the proviso that at least one of R R R and R is a carboxyalkyl, sulfoalkyl or sulfoalkoxyalkyl group; Y is hydrogen atom, chlorine atom, an alkyl group or an alkoxy group; Y is hydrogen atom or an alkyl group, with the proviso that Y is methyl when Y; is chlorine atom; Z is an atomic grouping capable of forming, together with the adjacent nitrogen and carbon atoms, a heterocyclic ring such as thiazoline, benzothiazole, benzose'lenazole, etc.; X is an anion; and r, m and n are each 1 or 2.

For the purpose of long term storage or reproduction of various printed matters including ofiicial documents, bonds, drawings, etc., photo-recording using microfilm is widely known. In such case, the color of the original to be photographed varies over the entire range of the visible spectrum. Further, the above-said photo-recording is usually made under a tungsten lamp having many number of absorptions in the long wavelength region. Therefore, the inherent sensitivity of the usual silver halide photographic emulsion is not sufiicient if said emulsion is intended to be used in a light-sensitive photographic material for copying art such as microfilm recording. For this purpose, it is necessary to have the usual silver halide photographic emulsion panchromatically sensitized.

It is an object of the present invention to provide a light-sensitive silver halide photographic emulsion having strengthened sensitivity over the entire visible spectrum and particularly at long wavelengths and further having good sharpness and stability.

We have now found that a light-sensitive silver halide photographic emulsion added to two or three members of the compounds of the above-indicated general Formula I in combination with one member of the compounds of the above-indicated general Formula II can show the desired improved sensitivity for microfilm recording application.

Typical compounds of the general Formullas I and II are listed below, without limiting the scope of this invention thereto.

Compounds of the general (ormula (I) Compounds of the General Formula (II) -01 [I C=CH-CH=CHC 1 01 N '\$N 432E 115 No. 12 C211;

0 1l: CH-

c=orr-on=on--o N $.11. onshor CzHs o I!I\ 1 \C=CH-CH=GH-C/ Er onto- -o1 N 9N hmomooou $.11,

The joint use of two or three compounds of the general Formula I with a compound of the general Formula II enables one to obtain such particular spectral sensitization of a light-sensitive silver halide emulsion as has never been observed by the sale use of the individual compounds. Thus, the photographic emulsion can be imparted with sufiicient spectral sensitivity over the entire visible spectrum, so that the said emulsion is excellent in photo- .graphic reproductviity. Further, this emulsion, when used for a microfilm can show good photographic characteristics. A still further advantage of this invention is that the distribution of sensitivity maxima can be optionally determined by varying the types and proportions of the compounds of the general Formulas I and 11. Furthermore, the sensitizing compounds used in this invention do not cause any adverse interaction with other photographic additives which may be present in the emulsion. A microfilm prepared from the emulsion of the invention is entirely free from deterioration of photographic properties (e.g. decrease of spectral sensitivity, etc.) during storage.

All the combinations of any two or three of the compounds of the general Formula I with any one of the compounds of the general Formula II are effective for the purpose of the invention. As stated above, however, the particular combination wherein at least one of the sensitizing dyes used has a solubilizing carboxyalkyl or sulfoalkyl substituent is preferred because color staining which is usually observed after development can be remarkably decreased as the result of increased hydrophilic property.

Addition of the compounds of the general Formulas I and II to a silver halide photographic emulsion may be made in a conventional manner. For example, these compounds are dissolved into a water-miscible organic solvent such as methanol, ethanol, etc., to give a solution which is then added to a photographic emulsion. Alternatively, a

in the range of -200 mg. per kilogram of the photo- G. Sodium carbonate (monohydrate) 30.0 Potassium bromide 5.0

Water to make up 1.0 l.

The results of measurement of photographic speed and color staining are set forth in Table 1. For comparison, the test results of light-sensitive silver halide photographic films sensitized by the sole use of individual sensitizing dyes are also shown in Table l. The values for color staining is expressed as color density measured by using a filter.

TABLE 1 Relative speed Compound(s) used White Green Red Compound Amount Compound Amount Compound Amount light light light Color number (mL) 1 number (ml.) K number (ml.) 1 (W) (R) G/W R/W stain 1 0.1% MeOH solution added to 1 kg. emulsion.

graphic emulsion. Any types of light-sensitive silver halide emulsions can be sensitized according to the present invention and typically include silver chloride, silver bromide, silver iodo'bromide, silver chlorobromide and silver chloroiodide emulsions. The light-sensitive silver halide photographic emulsion sensitized according to this invention may contain gold sensitizer, sulfur sensitizer, reductive sensitizer or polyalkyleneoxide sensitizer, and further may contain any known photographic additives such as stabilizer, coating aid, hardener, etc.

The present invention will now be explained in detail in connection with the following examples without limiting the scope of the invention thereto.

EXAMPLE 1 A silver chlorobromide solution for copying use is prepared, which contains 50 mol. percent of this emulsion, just before the completion of the second ripening, the indicated amount of various compounds set forth in Table 1 is added in the form of an 0.1% methanol solution at a high temperature. Then, the emulsion is coated on a film base and dried.

The light-sensitive silver halide photographic film (microfilm) thus obtained has good spectral sensitivity over the entire visible spectrum and is particularly excellent in spectral sensitivity at long wavelengths. This photographic film does not suffer from any interaction due to the coexistence of the sensitizers and photographic additives and is entirely free from color staining after development. When this film is used in copying, it is possible to obtain good reproduction from an original having spectral absorptions over the entire visible spectrum even by using a. tungsten lampas light source.

The photographic film is exposed to light according to the JIS method K-7609 and then treated at 20 C. for 4 minutes with a developer of the following formulation:

Metol 1.0 Sodium bisulfite (anhydrous) 75.

Hydroquinone As is apparent from the above table, the microfilms of the present invention are highly improved in photographic speed to white light in comparison with those prepared by the sole use of the individual compounds of the general Formula I and II. Further, the films of this invention have an increased ratio of both G/W and R/W. Good spectral sensitivity over the entire visible spectrum is obtained.

EXAMPLE 2 The same silver chlorobromide emulsion as used in Example 1 is subjected to a second ripening with a gold sensitizer to obtain maximum sensitivity. Just before the completion of said second ripening, each one kilogram portion of the emulsion is added at a high temperature with the indicated amount of varying compound in the form of an 0.1% methanolic solution, as shown in Table 2. After the completion of the second ripening, the emulsion is added with an optimum amount of 4-hydroxy- 6-meth-yl-1,3,3a,7-tetrazaindene. The thus obtained emulsion is coated on a film base and then dried.

The light-sensitive silver halide photographic film (microfilm) has good spectral sensitivity over the entire visible spectrum and is particularly excellent in spectral sensitivity at long wavelengths. This photographic film does not sulfer from any adverse effect due to the coexistence of the sensitizers and photographic additives and is entirely free from color staining after development. Further, there is not observed any deterioration of photographic properties even after the storage of the film for a long period of time. When this film is used in copying, it is possible to obtain good reproduction from an original having spectral absorptions over the entire visible spectrum even by using a tungsten lamp as light source.

The photographic film is exposed to light according to the 118 method K-7609 and then treated with a developer in the same manner as in Example 1. Photographic speed and fog are set forth in Table 2. For comparison, the test results of light-sensitive silver halide photographic films sensitized by the sole use of individual sensitizing 9.0 dyes are also shown.

Sensi- 80% RH tlvity maxi- White Green Red mum light light light m Fresh White Green Red light light light Fog TABLE 2 Cmpound(s) used Amount Compound Amount Compound Amount Compound Amount (ml.) 1 number (1111.) 1 number (mL) 1 number number Compound number @8833 gag As is apparent from the above table, the light-sensitive silver halide photographic films of the present invention are highly improved in spectral sensitivity in comparison E E 353533 with those prepared by the sole use of the individual comi E pounds of the general Formulae I and II. Further these 5 i l films have good spectral sensitivity over the entire visible i fi fi spectrum. Stability of the films is satisfactory to make 3 them free from fogging, decrease in photographic speed, 5 etc., over along period of time. :ggggggggg In the attached drawings, FIG. 1 is a spectral sensitivity curve of the silver chlorobromide emulsion used as the starting material of this example; FIG. 2 (I), (II) and MNNMNNNNN (III) are spectral sensitivity curves of the said emulsion when added with each of the compounds No. (1), No. (4) and No. (12) respectively; and FIG. 3 is a spectral ggg gggg sensitivity curve of the said emulsion when added with the i combination of the compounds No. (l), (4) and (12) according to the present invention. As is clear from the emulsion of the invention is highly improved in spectral 53133553353 drawing, the light-sensitive silver halide photographic sensitivity over the entire visible spectrum in comparison 888228223 with a photographic emulsion sensitized with a single com- H F1 F '1 pound of the general Formulas I and H.

What is claimed is: ggggggggg 1. A light-sensitive silver halide photographic emulsion o'de'c'ddc'dc' for microfilm, which comprises in combination two or I I three sensitizing dyes of the compounds of the general Q83 5 512382 Formula I:

seaeaasa r r N-C=CHC=CH-C=N E o I R; Ra a (X )rlilil (I) 8812E and one sensitizing dye of the compounds of the general Formula II:

wherein R R R and R are independently selected from the group consisting of a lower alkyl group, a carboxyalkyl group or a sulfoalkyl group, with the proviso that at least one of R R R and R is a carboxyalkyl, sulfoalkyl or sulfalkoxyalkyl group; R is hydrogen atom or a lower alkyl group; R is a lower alkyl group; y is hydrogen atom, chlorine atom, a lower alkyl group or a lower alkoxy group; Y is hydrogen atom or a lower alkyl group with the proviso that when Y is chlorine, Y is methyl; Z is a group capable of forming, together with the adjacent nitrogen and carbon atoms, a heterocyclic ring; X is an anion; and r, n and m are each 1 or 2.

2. A light-sensitive silver halide photographic emulsion for microfilm use, as claimed in claim 1, wherein said combination consists of 3,3'-diethyl-thiazolino-carbocyanine iodide, 3,3 sulfoethoxyethyl 9 methyl-thiacarbocyanine triethylamine and (3 carboxyethyl 5 methoxybenzoxazolo) 1,3 diethyl 5,6 dichloro-benzimidazolo)-carbocyanine bromide.

3. A light-sensitive silver halide photographic emulsion for microfilm use, as claimed in claim 1, wherein said combination consists of 3,3 dicarboxyethyl-thiazolinocarbocyanine bromide, 3,3 hydroxyethyl 9 methylthia-carbocyanine iodide and (3 ethyl 5 chloro 6- methyl-benzoxazolo) (1 ethyl 3 sulfobutyl 5,6- dichloro-benzimidazolo)-carbocyanine.

- 4. A light-sensitive silver halide photographic emulsion for microfilm use, as claimed in claim 1, wherein said 100 on 30 No. (4). 50 do 50 -d0.- 50 do 40 do 0.1% MeOH solution added to 1 kg. emulsion.

9 combination consists of 3,3 diethyl-thiazolino-carbocyanine iodide, 3,3 disulfobutyl 9 methyl-thia-carbocyanine iodide and (3 ethyl 5 chloro 6-methylbenzoxazolo) (1 ethyl 3 sulfobutyl 5,6-dichlorobenzimidazolo)-carbocyanine.

5. A light-sensitive silver halide photographic emulsion for microfilm use, as claimed in claim 1, wherein said combination consists of 3,3 diethyl-thiazolino-carbocyanine iodide, 3,3 disulfobutyl 9 methyl-thia-carbocyanine iodide, 3,3'-disulfobutyl-9-methyl-benzselenazolocarbocyanine and (3-ethyl-benzoxazol0)-(1-ethyl-3-ethyl- 5,6-dichloro-benzimidazolo)-carbocyanine iodide.

6. A microfilm which comprises a film base and, supported thereon, a layer of the smulsion as claimed in claim 1.

10 References Cited UNITED STATES PATENTS 3,173,791 3/1965 Kalenda 96104 3,431,110 3/1969 Ficken et al. 96104 5 3,463,640 8/1969 Ficken et a1 96--104 FOREIGN PATENTS 1,137,701 6/1957 France 1-7 10 WILLIAM D. MARTIN, Primary Examiner B. D. PIANALIO, Assistant Examiner US. Cl. X.R. 15 96-137 

